Use of merocyanine compounds in photothermosensitive systems

ABSTRACT

A light-sensitive system including an intimate mixture of a light-insensitive silver salt which yields a visible change upon reduction, and light-sensitive silver halide in an amount sufficient to catalyze reduction of the light-insensitive silver salt upon exposure of the system to light followed by heating in the presence of a reducing agent, the mixture being characterized by including a tri-nuclear merocyanine dye capable of sensitizing the mixture to the longer wavelength portion of the visible spectrum. Also described are novel merocyanine dyes and lightsensitive sheets containing the above-described mixture.

United States Patent 1 Lea 1 1 March 6, 1973 [75] Inventor: Bernard A. Lea, London, England [73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn.

[22] Filed: Sept. 29, 1970 21 Appl. No.: 76,628

[30] Foreign Application Priority Data Oct. 3, 1969 Great Britain ..47,850/69 [52] US. Cl. ..4 ..96/114.1, 96/114.6, 117/368, 96/127 [51] Int. Cl. ..'...G03c 1/02 [58] Field of Search ..96/ll4.l, 114.6, 127, 139, 96/140; 250/651; 1l7/36.8, 36.9

2,635,961 Carroll ..96/127 Primary Examiner-J. Travis Brown Assistant Examiner-Judson R. Hightower Attorney-Kinney, Alexander, Sell, Steldt & Delahunt [57] ABSTRACT A light-sensitive system including an intimate mixture of a light-insensitive silver salt which yields a visible change upon reduction, and light-sensitive silver halide in an amount sufficient to catalyze reduction of the light-insensitive silver salt upon exposure of the system to light followed by heating in the presence of a reducing agent, the mixture being characterized by including a tri-nuclear merocyanine dye capable of sensitizing the mixture to the longer wavelength portion of the visible spectrum. Also described are novel merocyanine dyes and light-sensitive sheets containing the above-described mixture.

18 Claims, No Drawings USE OF MEROCYANINE COMPOUNDS IN PHOTOTH ERMOSENSITIVE SYSTEMS This invention relates to photo-sensitive compositions and more especially to the sensitization of such compositions, and also to certain compounds which act as sensitizers for such compositions.

One particular type of photo-sensitive composition comprises an intimate mixture of a light-sensitive silver halide and another silver compound such as a silver salt of an organic acid, e.g., silver behenate or silver saccharine, which latter silver compound upon reduction gives a visible change and which is substantially light-insensitive. Such a mixture is usually prepared in suspension and spread on a suitable substrate. When dry, the resulting layer is exposed to a light image and thereafter a reproduction of the image can be developed by heating the layer in the presence of a reducing agent such as hydroquinone or certain substituted phenols.

Because the exposure and development of the layer occur without using water, these materials are often mixtures to light of wavelengths at the red end of the spectrum, the results have been poor. In particular, attempts have been made to use cyanine dyes which, in conventional gelatino silver halide photographic materials, act as excellent sensitizers for the longer wavelengths of light and particularly red light. However, these cyanine dyes tend to give only poor results when used to sensitize dry silver materials.

It is, therefore, an object of the invention to improve the sensitization of these photo-sensitive silver halide and other silver compound mixtures to light of longer wavelengths and particularly to red light and also to provide various dyes for this purpose.

According to the invention there is provided a lightsensitive composition comprising an intimate mixture of a substantially light-sensitive silver compound which upon reduction gives a visible change and sufficient silver halide to catalyze this reduction to give a visible change in those areas where the silver halide has been exposed to light and the mixture is heated in the presence of a reducing agent, and a merocyanine dye having the general formula:

referred to as dry silver light-sensitive materials. Examples of these dry silver materials are found in British Pat. No. 1,110,046 which describes a photographic material in which minor amounts of a photo-sensitive silver halide catalyst-progenitor are associated in catalytic proximity with major amounts of a heat-sensitive oxidation-reduction image forming reaction mixture which reacts more rapidly under the influence of the catalyst which results upon exposure of the silver halide.

When the mixture is exposed to light, a latent image is believed formed in the silver halide. Thereafter, the silver compound can be reduced by heating with the reducing agent, this reduction being catalyzed imagewise by the light-exposed silver halide. By a suitable choice of temperature, the reduction of the silver compound can be catalyzed in the light-exposed areas to give a visible darkening while any slight reduction which occurs in the non-light exposed areas is insufficient to give a marked change. Of course, because the silver halide acts as a catalyst, only very small amounts of it are required, e.g., 0.1 to 10 percent by weight of the mixture.

The mixture of silver halide and other silver compound alone is not evenly sensitive to all parts of the radiation spectrum and accordingly one or more sensitizing dyes may be added. Although attempts have been made using dyes to improve the sensitivity of the in which k and l are each 0 or 1 and, when k is 0, l is 1 and when k is l, l is 0, Q represents S, -Se, CH=CH, -O-,

where R represents a lower alkyl group or a lower alkyl group containing as ester group, (e.g., -CH -CH -COOC H or CH -CH O.COCH m and n are each 0 or 1; R represents an alkyl, hydroxyalkyl, carboxyalkyl or sulfoalkyl group (preferably alkyl), R represents an aryl or aralkyl group or any of the groupings represented by R (preferably alkyl or carboxyalkyl); R and R each independently of one another represents a hydrogen atom or a lower alkyl group; X and Y each independently of one another represents a hydrogenor halogen atom or a lower alkyl, alkoxy, (e.g., methoxy), aryl, amino or acylamino group, or X and Y together constitute a divalent methylene dioxy group or represent the carbon atoms required to form a fused on carbon ring, and Z represents -S-, O-,

so as to complete a heterocyclic ring such as, for example:

and R and R which may be momma or different; stitu ted phenols such as methylhydroxy-naphthalene,

each represent a hydrogen atom or any of the methyl gallate,catechol, phenylene diamine, p-aminogroupings represented by R including the groupings phenol and l phenyl 3 pyrazolidone. The reducing RCOOH and R'SO H where R represents a lower al- 10 agent preferably is incorporated into the light-sensitive kylene group. composition prior to coating of the composition on a It is found that these merocyanine dyes give excellent support. In another embodiment, the composition can sensitization of dry silver materials to light in the be placed in contact with the reducing agent after exorange and red end of the spectrum. Thus, it is possible posure to light. For example, a light-sensitive coating to make these materials sensitive to the full breadth of may be exposed to a light image and the image may the visible spectrum and to some extent beyond the then be developed by heating this coating in contact edges of the visible spectrum. In particular, the photowith a layer containing the reducing agent. The stability sensitive materials of the invention have been found to of the composition is also improved by incorporating in have useful sensitivity at the far red end of the visible the composition a small amount of a stabilizer such as spectrum and so they are found to be useful in recoding an acid stabilizer, e.g., succinic acid, benzoic acid or images from certain red laser beams, e.g., a heliumsalicyclic i neon laser. The silver halide can be present in quite small The tri-nuclear merocyanine dyes of the invention amounts, e.g., 0.1 to 10 percent by weight of the mix,-

. m b i o d i th h t itiv mixt r ture of silver compounds. it can be'added as such to the before they are spread on a support or may be consubstantially light-insensitive silver compound, or silver tacted with (e.g., coated upon) a layer of the light-senhalide can be formed in situ by adding a soluble halide, sitive mixture before exposure to an image. Preferably, -g-, a ry o ium halide t0 the Substantially however, th d is i r t d as a l i i a light-insensitive silver compound. The latter course is suitabl l t t -i hl h l h l, 0 preferred since this ensures a very intimate mixture of chloroform or acetone) into the light-sensitive mixture the Silver compounds and improves the catalytic effect before the latter is spread on a s itable su rt, of the light-exposed silver halide. The silver halide can, These dyes may be incorporated in amounts of fr m for example, be the chloride, bromide or mixture of 0.01 to 2.0 g and preferably from 0.4 to 1.0 g of dye per m l lher silver halides. gram mole of total silver in the light-sensitive mixtures. Of u e, the light-sensitive compositions of the in- As noted above the light-sensitive composition will norven ion can include one or more other sensitizing dyes mally be spread for use on a support, suitable supports to improve their sensitivity to parts of the spectrum including, for example, paper, polyester or polyamide {ha ling i Wavelengths referred to abovefilm bases, and glass. The composition will normally be According toanother aspect of the invention, meroprepared as a solution or suspension which is spread as 40 cyanine dyes are provided which have the following a layer on the support and then the solvent or vehicle is general formula:

evaporated away to leave a dry photosensitive layer. If l, are as defined desired, a coating aid or binder such as polyvinyl buabove, and R and R which may be the same or diftyra], polymethyl methacrylate, ll l t t ferent, are as defined above with the proviso that R or polyvinyl acetate, cellulose acetate-propionate and cel- R5 or both R and R represent the grouping lulose acetate butyrate, can be incorporated'in the R1COOH (P y) 3" Where R7 is as light-sensitive mixture. The support may, of course, defined abovebear other layers as well as the light-sensitive layer referred to above, such as a layer containing a reducing The f used in the invention can be agent for the light-insensitive silver compound, in conprepared m any convemem i In 99? tact with thelishbsensitivelawn ever, they are prepared by heating an initial mero- The substantially light-insensitive silver compound is 0 cyanine dye having the general formula: suitably a silver salt of an organic acid. Examples include silver behenate, silver caprate, silver laurate,

silver myristate, silver palmitate, silver stearate, silver X S arachidate and silver saccharine. (Q)kC=(OH-CR )m=.C \C=(CH-CR3),.=S

The reducing agent for this substantially light-inseni 1 sitive silver compound can normally be quite mild. T g l Suitable examples include hydroquinone and sub- 'ample, in Hamer, Cyanine Dyes and Related Com methyl-toluene p-sulfonate, which is preferably in excess. Desirably an inert solvent is also present. The quaternary derivative thus formed is then separated 5 from excess reagents and condensed with a compound having the general fonnula:

z Hz=(GHCR )n=O c=s II I o R4 pounds, lnterscience Publishing Co., 1964; United Kingdom Pat. Specifications Nos. 428,222; 428,359 and 519,895, and JACS, 73, 5326-8.

Examples of merocyanine dyes which have beenfound to give excellent sensitization of the light-sensitive compositions according to the invention are the following dyes A, B, C and D:

A. i s

C=CHCH=C 6 useful in the sensitization of light-sensitive compositions according to the invention, while Example 39 illustrates the use of these dyes in compositions according to the invention.

EXAMPLE 1 3-Ethyl-5 3-ethyl-2-benzothiazolinylidene) ethylidene] -2(3-ethyl-4-oxo-2-thio-5-thiazolidinylidene)- 4-thiazolidone. (Dye A) 3 -Ethyl-5 Zi -ethyl-2-be,nzoithiazolinylidene) ethylidene] -2-thio-4-thiazolidone (14 g) was heated with methyl toluene p-sulphonate (28 g) at C for 4% hours. Excess ester was then washed away with dry ether. The residue was mixed with a mixture of 3-ethyl- 2thiothiazolid-4-one (6.4 G), ethanol (300 ml) and triethylamine (10 ml). After heating under reflux for 25 minutes the mixture was filtered hot and the residue washed with hot ethanol and then ether. The crude dye (14 g) was purified byboiling first with methanol (350 ml) and then benzene (300 ml) to leave the dye (12 g) as dark green micro crystals with a melting point of 323C with decomposition.

I EXAMPLE 2 3-Ethyl-5 l -ethyl- 1 ,2-dihydroquinolinylidene-2 )ethylidene]-2( 3-carboxymethyl-4-oxo-2-thio-5thiazolidinylidene)-4-thiazolidone (Dye B) 3-Ethyl-5 l-ethyll ,2-dihydroquinolinylidene- 2 )ethylidene] -2-thio-4-thiazolidone (12.8 g) was heated with methyl toluene P-sulphonate (20 g) at l30Cfor 4% hours. Excess ester was then washed away with dry ether. The residue was mixed with a mixture of 3-carboxymethyl-2-thio-thiazolidone (7.3 g), ethanol (250ml) and triethylamine (11.2 ml). After heating under reflux for 15 minutes the mixture was cooled and acidified with acetic acid (1 lml). The product separated slowly and was collected on a filter and washed with ethanol and ether. Purificationwas achieved by first boiling with methanol (300 ml) and then dissolving the residue as the triethylamine salt in ethanol (5 liters) and reprecipitating it with acetic acid. The resulting brilliant green crystals (8.7 g) had a melt ing point of 241C, decomposing at 270C.

EXAMPLE 3 3-n-l-leptyl-5 3-ethyl-2-benzothiazolinylidene) ethylindene] -2 (3-carboxymethyl-4-oxo-2-thio-5- thiazolidinylidene )-4-thiazolidone (Dye C) 3-n.-Heptyl-5 [(3-ethyl-2-benzothiazolinylidene) ethylidene] -2-thio-4'-thiazolidone (26.75 g) was heated with methyl toluene p-sulphonate (35 g) at C for 4 hours. Excess ester was then washed away with dry ether. The residue was mixed with a mixture of 3-carboxymethyl-24-thiazolidone (l 1.2 g), ethanol (800 ml) and triethylamine (17.9 ml). After heating under reflux for 15 minutes the mixture was cooled slightly and acidified with acetic acid (18 ml) and after standing was filtered. The crudedye (11.8 g) was purified by solution as the triethylamine salt in hot methanol (280 ml) and reprecipitated by the addition of glacial acetic acid as glistening dark green crystals (7.7 g) with a melting point of 265 to 270C.

EXAMPLE 4 3-n-l-leptyl-5[(3-ethyl-2-benzothiazolinylidene)ethy- 7 lidene]-2(3-carbethoxyethyl-4-oxo-2-thio-5- thiazolidinylidene)-4-thiazolidone The dye from Example 3 (3g) was heated under reflux for 1 hour in ethanol (1 liter) containing acetic acid (2ml) and the triethylamine (25 ml) was added and the mixture was left to stand. On cooling green crystals were deposited and filtered off. Crystallization from. benzene 100 ml) gave a green crystalline product (0.5 g) with a melting point of 244 to 245C.

EXAMPLE 3-Ethyl-5 3-ethyl-2-benzothiazolinylidene )ethylidene ]-2( 3-carboxymethyl-4-oxo-2-thio-5 -thiazolidinylidene )-4-thiazolido ne 3 -Et'hyl-5 3-ethyl-2-benzothiazolinylidene )ethylidene]-2-thio-4-thiazolidone (2.1g) was heated with methyltoluene p-sulphonate (2.0 g) at 130C for 4 hours. Excess ester was then washed away with dry ether. The residue was mixed with 3-carboxymethyl-2- thiothiazolid-4-one 1.15 g), ethanol (75 ml) and triethylamine (1.7 ml). After heating under reflux for 15 minutes, the mixture was cooled and, after standing,

was filtered. The crude dye-(2.0 g) was purified'by crystallization as the triethylamine salt in hot meth oxyethanol. The product dye was obtained as deep green crystals (1.4g) with a melting point of 306 to 307C with decomposition.

EXAMPLE 6 3 -n-l-leptyl-5 3-ethyl-2-benzothiazolinylidene )ethylidene]-2(3-ethyl-4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone 3 -n-l-leptyl-5 3 -ethyl-2- ,benzothiazolinylidene )ethylidene] -2-thio-4-thiazolidone (8.4 g) was heated with methyl toluene p-sulphonate (17.0 g) at 140C for 5 hours. Excess ester was then washed away with dry ether. The residue was mixed with 3-ethyl-2-thiothiazolid-4-one (3.2 g) ethanol (200 ml) and triethylamine (2.8 ml). After heating under reflux for 15 minutes the mixture was cooled and filtered. The crude dye (5.9 g) was crystallized from benzene (150 ml) and obtained as glistening green crystals with a melting point of 240 to 242C.

EXAMPLE 7 3 -ethyl-5 3-ethyl-2-benzothiazolinylidene )ethylidcne -4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone 3-Ethyl-5 3-ethyl-2-benzothiazolinylidene )ethylidene] -2-thio-4-thiazolidone (1.4 g)'was heated with methyl toluene p-sulphonate (2.0 g) at 130C for 4 hours. Excess ester was then washed away with dry ether. The residue was mixed with 3-n-heptyl-2-thiothiazolid-4-one. (0.92 3) ethanol (50 ml) and triethylamine (0.56 ml). After hearing under reflux for l5 minutes, the mixture was cooled slightly and, after standing, was filtered. The crude dye (0.9 g) was purified by crystallizing from benzene (300 ml). The product dye was obtained as deep magenta crystals (0.6 g) with a melting point of 322 to 323C.

EXAMPLE 8 3-Carboxymethyl-5 [(3-ethyl-Z-benzothiazolinylidene)ethylidene]-2 (3-n-heptyl-4-oxo-2-thio-5 [(3- ethyl-2-benzothiazolinlyidene) e'th'ylidene1-2-thio-4- thiazolidone (3.6 g) was heated with methyl toluene psulphonate (5.0 g) at C for 4 hours. Excess ester was then washed away with dry ether. The residue was mixed with 3-n-heptyl-2-thio-thiazolid-4-one (2.3 g), ethanol (125 ml) and triethylamine (1.4 ml). After heating under reflux for 15 minutes the mixture was cooled and filtered. The crude dye (9.4 g) was twice crystallized from benzene to give a product dye with a melting point of 230 to 235C.

EXAMPLE 9 3-n-l'leptyl-5 [(3-ethyl-2-benzothiazo1inylidene)ethylidene]-2(3-n-heptyl-4-oxo-2-thio-5-thiazolidinylidene 4-thiazolidone 3-n-l-leptyl-5 [(3-ethy1-2-benzothiazolinylidene )ethy lidene]-2-thio4-thiazolidone (13.8 g)-w as heated with methyl toluene p-sulphonate (22.0 g) at C for 4 hours. Excess ester was then washed away with dry ether. The residue was mixed with 3-n-heptyl-2-thiothiazolid-4-one (7.7g) ethanol (200 ml) and triethylamine (4.7 ml). After heating under reflux for 20 minutes, the mixture was cooled slowly and after standing was filtered. The crude dye was crystallized from a, mixture of benzene (100 ml)and cyclohexane ml) to give dark green crystals having a melting point of to 197C.

' 3 EXAMPLE 10 3-Ethyl-5 5 -chloro-3-ethyl-2-benzothiazolinylidene)ethylidene]-2 (3-carboxymethyl-4-oxo-2-thio- S-thiazolidinylidene) 4-thiazolidone (Dye D) 3-Ethyl- 5 5-chloro-3-ethyl-2-benzothiazolinylidene)ethylidene] -2-thio-4-thiazolidone (9.6g) was heated with methyl toluene P-sulphonate (15.0 g) and xylene (50 ml) at 140C for 2 hours. Cooled, filtered and washed with dry ether. The residue was mixed with 3-carboxymethyl-24-one (4.9 g), 90

percent aqueous ethanol (350 m1) and triethylamine (710 ml). After heating under reflux for 15 minutes, the mixture was cooled slightly, acidified with glacial acetic acid (12.5 ml) and, after standing, was filtered. The crude dye (5.0 g) was purified by solution as the triethylamine salt in hot 90 percent aqueous ethanol (1500 ml) and reprecipitated by the addition of glacialacetic acid, as deep green crystals(3.7 g) with a melting point of 230C.

EXAMPLE l1 EXAMPLE 12 3-Ethyl-5[(5-chloro-3-ethyl-benzothiazolinylidene)ethylidene] -2(3-n-heptyl-4-oxo-2-thio-5- thiazolidinylidene)-4-thiazolidone 3-Ethyl-5[(5-chloro-3-ethyl-2-benzothiazolinylidene) ethylidenel-2-thio-4-thiazolidone (3.1 g) was heated with methyl toluene p-sulphonate (5.0 g) at 140C for 3 hours. Excess ester was then washed away with dry ether. The residue was mixed with 3-n-heptyl- 2-thio-thiazolid-4-one (1.85 g) ethanol (100 ml) and triethylamine (1.1 ml). After heating under reflux for 15 minutes, the mixture was cooled slightly and filtered. The crude dye (1.6 g) was purified by boiling with benzene to leave a magenta solid (0.6 g) with -a melting point of 270C.

EXAMPLE 13 3-Ethyl-5[( l-ethyl-l ,2-dihydroquinolinylidene-2)ethylidene -2 (3-carboxy-pentyl-4-oxo-2-thio-5- thiazolidinylidene)-4-thiazolidone 3-Ethyl-5 1 -ethy1-1 ,2-dihydroquinolinylidene- 2)ethylidene]-2-thio-4-thiazolidone (3.4 g) was heated with methyl toluene p-sulphon'ate (4 g) at 140C for 4 hours. Excess ester was washed away with dry ether. The residue was mixed with 3-carboxypentyl-2-thiothiazolid-4-one (2.4 g) and pyridine (30 ml) and heated at 100C for 1 hour. The crude dye (3.4 g) was filtered off after cooling and purified by solution in hot 90 percent aqueous ethanol as the triethylamine salt and acidifying to pH 3 with concentrated hydrochloric acid at C. The resulting precipitated dye was obtained as deep green plates (2.4 g) with a melting point of 293 to 295C.

EXAMPLE 14 EXAMPLE 15 3-Ethyl-5 1-e.thyl-1 2-dihydroquinolinylidene-2)ethylidene]-2 (3-n-heptyl-4-oxo-2-thio-S-thiazolidinylidene)-4-thiazolidone 3-Ethyl-5[( l-ethyl-l ,2-dihydroquinolinylidene- 2)ethylidene]-2-thio-4-thiazolidone (4.1 g) was heated with methyl toluenep-sulphonate (8.0 g) at 130C for 130 hours. Excess ester was washed away with dryether. The residue was mixed with 3-n-heptyl-2-thiothiazolid-4-one (2.8 g), ethanol (150 ml) and triethylamine (1.7 ml) and heatedunder reflux for 15 minutes. The crude dye (3.5 g) was filtered off after cooling and crystallized from benzene 15C ml) to give the'product dye as bright green crystals (1.9 g) with a melting point of 228C.

EXAMPLE 16 EXAMPLE 17 3-n-l-leptyl-5 3-ethyl-2-B-naphthathiazolinylidene)ethylidene]-2(3-carboxymethyl-4-oxo-2-thio-5- thiazolidinylidene)-4-thiazolidone 3-n-l-leptyl-5[(3-ethyl-Z-B-naphthathiazolinylidene) ethylidene]-2( 3-carboxymethyl-4-oxo-2-thio-5- thiazolidone (4.7 g) was heated with dry oxylene (16 ml) and methyl toluene p-sulphonate (6.0 g) at 140C for 2 hours. The mixture was filtered and the solids washed with dry ether. The residue was mixed with 3- carboxymethyl-2:thio-4-thiazolidone (1.9 g) anddry pyridine ,(25 ml). After heating under reflux for 15 minutes the mixture was cooled and poured in 90 pen cent aqueous ethanol (75 ml). After acidifying with glacial acetic acid (25 ml) the product was filtered off. The crude dye (5.6 g) was purified by solution in 90 percent aqueous ethanol (850 ml) as the triethylamine salt and precipitated by the addition of glacial acetic acid to give dark green crystals (3.9 g) with a melting point of 298C..

EXAMPLE 18 3-n-l-leptyl-5[(3-ethyl-2-benzothiazolinylidene)ethylidene]12(1,3-dimethyl-4-oxo-2-thio-5-iminazolidinylidene)-4-thiazolidone 3-n -l-leptyl-5[(3-ethyl2-benzothiazolinylidene) ethylidenel-2-thio-4-thiazolidone (4.2 g) was heated with dry xylene (10 ml) and methyl toluene psulphonate (6.0 g) at 140C for 2 hours. The mixture was then cooled filtered and the solids washed with dry ether. The residue was mixed with 1,3-dimethyl-2-thiohydantoin (1.4 g), ethanol (20 ml) and triethylamine (1.4 ml) and heated under reflux for 20 minutes. The dye was filtered from the cooled reaction mixture and purified by boiling with ethanol (200 ml) to leave the product dye as dark green crystals (1.0 g) with a melting point of 184C.

EXAMPLE l9 ethanol (30 ml) and triethylamine (0.7 ml). After heating under reflux for. minutes, the mixture was cooled and the product removed by filtration. Afterwashing well with ethanol, the dye remained as bright green plates with a melting point of 263C.

EXAMPLE 20 3-n-l-leptyl-5 3-n-heptyl-2-benzothiazolinylidene)ethylidene]-2(4-oxo-2-thio-5-thiazolidinylidene)-4-thiazolidon'e 3-n-Heptyl-5 3 -n-heptyl-2-benzothiazolinylidene)ethylidene]-2-thio-4-thiazolidone (2.4 g) was heated with dry Xylene (10 ml) and methyl toluene psulphonate (3.0 g) at 140C for 2 hours. The mixture was filtered and the solids washed with dry ether. The residue was mixed with 2-thio-thiazolid-4-one (0.67 g),

' was filtered and the solids washed with dry ether. The

ethanol (30 ml) and triethylamine (0.7 ml). After heating under reflux for 10 minutes, the mixture was cooled and the dye removed by filtration. The crude dye (0.9 g) was dissolved in chloroform and drowned into methanol to give bright green crystals (0.6 g) having a melting point of 277C.

EXAMPLE 21 3 -n'1-leptyl-5 (3 -ethyl-2-benzothiazolinylidene )ethylidene]-2(3-ethyl-4-oxo-2-thio-5-oxazolidinylidene)-4- thiazolidone 3 -n-Heptyl-5 3-ethyl-2-benzothiazolinylidene) ethylidene] -2-thio 4-thiazolidone (4.2 g) was heated with dry xylene and methyl toluene p-sulphonate (6.0 g) at 140C for 1% hours. The resulting mixture was filtered and the solids washed with dry ether. The residue was mixed with 3-ethyl-2-thio-oxazolid-4-one (1.6 g), ethanol (30 ml) and triethylamine (1.4 ml). After heating under reflux for 20 minutes the reaction mixture was cooled and the crude product (0.6 g) filter'ed off. Purification was obtained by solution in chloroformand drowning into methanol. The resulting magenta colored crystals (0.4g) had a melting point of 253C.

, EXAMPLE 22 3 C arboxymethy1-5( 3 -ethy1-2-benzothiazolinylidene 2( 3 -carboxymethyl-4-oxo-2-thio-5 -thiazolidinylidene 4-thiazolidone 3 -Carboxymethyl-5 3-ethyl-'2-benzothiazolinylidene)-2-thio-4-thiazolidone (7.0 g) was heated with dry xylene ml) and methyl toluenep-sulphonate (12.0 g) at 140C for 4 hours. The mixture was filtered and the solids washed with dry ether. The residue was mixed with a mixture of 3-carboxymethyl-2- thiothiazolid-4-one (3.8 g), 90 percent aqueous ethanol (50 ml) and triethylamine (10.0 ml). After heating under reflux for 15 minutes the mixture was cooled slightly and acidified wit glacial acetic acid (25 ml) and after standing was filtered. The crude dye (3.0 g) was purified bysolution as the triethylamine salt in hot 90 percent aqueous ethanol (400 ml) and reprecipitated by the addition of glacial acetic acid, as

orange red crystals (1.5 g) having a melting point of 270C.

EXAMPLE 23 3-Ethyl-5 3-ethyl-6-methyl-2-benzothiazolinyresidue was mixed .with 3-carboxymethyl-2-thiothiazolid-4-one (2.0 g) and pyridine (20 ml). After heating under reflux for 20 minutes, the mixture was cooled and filtered to obtain the crude product which was then purified by solution in hot 90 percent aqueous ethanol (250 ml) as the triethylamine salt and precipitated by the addition of excess glacial acetate acid. The product dye (0.9 g) was obtained as deep green crystals with a melting point of 305C.

M EXAMPLE ZT 3 -n-1-leptyl-5 3-ethyl-2-benzothiazolinylidene )isopropylidene -2( 3-carboxymethyl-4 oxo-2- thio-S-thiazolidinylidene )-4-thiazolidone 3-n-1-lepty1-5 3 -ethyl-2- benzothiazolinylidene )isopropylidene ]-2-thio-4=thiazo1idone (4.0 g)

was heated with dry xylene (10 ml) and methyl toluene p-sulphonate (7.0 g at 140C for 2 hours. The mixture was then filteredand the solids washed with dry ether. The solids were mixed with 3-carboxymethyl-2- thiothiazolid-4-one (2.0 g).and pyridine (30 ml). After heating under reflux for 20 minutes the mixture was cooled and filtered to obtain the crude product which was then purified by solution in hot percent aqueous ethanol as the triethylamine salt and precipitated by the addition of an excess of glacial acetic acid. The product dye (1.6 g) was obtained as dark magenta crystals with a melting point of 277C. 5

EXAMPLE 25 3-Ethyl-5 1 -ethyl- 1 ,2-dihydroquinolinylidene-2 )ethylidene]-2(3-ethyl-4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone p I 3-Ethyl-5 1 -ethyl-1 ,2-dihydroquinolinyldiene- 2)ethylidene]-2-thio-4-thiazolidone (4.2 g) was heated wit methyl toluene p-sulphonate (8.0 g) at C for 4 hours, then excess ester was washed away with dry ether. The residue was mixed with 3-e thyl-2;-thiothiazolid-4-one (2.0 g), ethanol ml) and triethylarnine (1.7 ml) and heatedunder reflux for; 15 minutes. The crude dye (2.0 g) was filtered off after cooking and crystallized from benzene (1,800 ml) to give the dye as deep green plates (1.6 g) witha melting point 0f315 t0319C.

EXAMPLE26 I 3-Ethyl-5 l-ethyl- 1 ,4-dihydroquinolinylidene-4)ethylidene]-2(3-ethyl-4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone 3-Ethyl-5 l-ethyl-l -,4-dihydroquinoliny1idene-4) ethylidenel-2-thio-4-thiazolidone (7.5 g) was heated withmethyl toluene p-sulphonate (15.08) at 130C for 4 hours. Then excess ester was washed away with dry minutes. The crude dye (4.6 g) was filtered off after cooling and crystallized from benzene (4,500 ml) to i give the dye as dark green crystals (2.6 g) with a gold reflex, and with a melting point of 303+ to 305+ C.

EXAMPLE 27 2-Ethyl-5 1 -ethyl- 1 ,4'dihydroquinolinylidene-4 )ethylidene]-2(3-carboxymethy1-4-oxo-2-thio-5- thiazolidinylidene-)-4-thiazolidone 3-Ethyl-5 l-ethyl- 1 ,4dihydroquinoliny1idene-4) ethylidene]-2-thio-4-thiazolidone (8.6 g) was heated with methyl toluene p-sulphonate (14 g) and dry xylene (50 ml) at 140C for 2' hours. The mixture was then filtered and theresidue washed with dry ether. The residue was next mixed with a mixture of 3-carboxymethyI-Z-thio-thiazolidone (4.8 g), 90 percent ethanol (50 ml) and triethylamine (7 ml) A ft er heating under reflux for 20 minutes the mixture was cooled and acidified with acetic acid (7 ml) The product dye separated and was collected on a filter and washed with ethanol and ether. Purification was achieved by dissolving the crude dye as the triethylamine salt in 90 percent ethanol (1 liter andreprecipitating it with hydrochloric acid; The resulting brilliant green crystals (2.5 g) had a melting point of 303C.

' EXAMPLE 2s 3 -n-1-leptyl-5 lethyl- 1 ,2-dihydroquinoliny1idene- 2)ethylidene1-2(4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone 3n-l-leptyl-5 1 -ethyll, ,2-dihydroquinoliriylidene-Z) ethylidene]-2thio-4-thiazolidone (2.1 g) was heated with dry' xylene (10 ml) and methyl toluene p- After washing well with ethanol, the crude dye (1.5 g)

was dissolvedin chloroform and precipitated with methanol as green plates(0.8 g) with a melting point of EXAMPLE 29 cooled and the product removed by filtratiomAfter I washing well withethanol, the dye remained as bright green plates EXAMPLE 30 3 -Ethyl'5 3-ethy1-2-benzoxazo1iny1idene)ethy1idene]- 2(3-n-hepty1-4-oxo-2-thio-S-thiazolidinylidene)-4- thiazolidone 3-Ethyl-5 3-ethyl-2-benzoxazolinylidene)ethylidene]-2-thio-4-thiazolidone (3.3 g) was heated with methyl toluene p-sulphonate (4.0 .g) at 140C for 3 hours. Excess ester was then was washed away with dry ether. The residue was mixed with 3-n-heptyl-2-thiothiazolid-4-one (2.3 g), ethanol (50 ml) and triethylamine. After being heated under reflux for 20 minutes, the mixture was cooledand filtered. The residue of crude dye (3.4 g) was crystallized from benzene (350 ml) to yield a magenta colored product with a melting point of 298 to 300C.

EXAMPLE 31 EXAMPLE 32 3-n-l-Ieptyl-5 3-ethyl-2-benzoxazolinylidene )ethylidene ]-2(4-oxo-2-thio-5-thiazo1idinylidene )-4- thiazolidone 3-n-1-leptyl-5 3-ethyl-2-benzoxazolinylidene )ethylidene]-2-thio-4-thiazolidone (2.0 g) was heated with dry xylene (10 ml) and methyl toluene p-sulphonate (3.0 g) at 140C for 2 hours. The mixture was then filtered and the solids washed with dry ether. The solids were mixed with 2-thio-thiazolid-4-one (0.67 g),

ethanol (30 ml) and triethylamine (0.7 ml). After heating under reflux for 20 minutes the mixture was cooled and filtered. The residue of crude dye (1.3 g) was purified by solution in chloroform and dilution with methanol. The resulting bright green crystals (0.75 g) had a melting point of 299C.

EXAMPLE as ethanol (50 ml) and triethylamine (2.8 ml). After heating under reflux for 15 minutes, the mixture was cooled and filtered. The crude dye (3.5 g) was purified by solution as the triethylamine salt in hot percent aqueous ethanol (440 ml) and rep'recipitated by the addition of glacial acetic acid, as bright green plates (2.5 g) with a melting point of 3 14 to 315C.

thiazolid-4-one 3-Ethyl-5 [(-acetamido-3-methyl-2-benzoxazolinylidene)ethylidene]-2(3-ethyl-4-oxo-2-thio-5- thiazolidinylidene)-4-thiazolidone 3-Ethyl-5 S-acetamido-3-methyl-2-benzoxazolinylidene )ethylidenel-2-thio-4-thiazolidone (0.9 g) was heated with dry xylene (4ml) and methyl toluene psulphonate (1.5 g) at 140C for 2% hours. The mixture was filtered and then the solids washed with dry ether. Then the solids were mixed with 3-ethyl-2-thio- (0.4 g), ethanol (15 ml) and triethylamine (0.4 ml). After heating under reflux for 15 minutes the mixture was cooled and'filtered. The crude dye (0.75 g) was purified by boiling with ethanol (25 ml) to give dark green crystals with a melting point of 308 to 310C (with decomposition).

EXAMPLE 35 3 -n-Heptyl-5 6-ethoxy-3-ethyl-2-benzoxazolinylidene)ethylidene ]-2(3-carboxymethyl-4-oxo-2-thio-5- thiazolidinylidene)-4-thiazolidone 3 -n-Heptyl-5 6-ethoxy-3-ethyl-2-benzoxazolinylidene)ethylidene]-2-thio-4-thiazolidone (17.7 g) was heated with dry xylene (75 ml) and methyl toluene psulphonate (18.0 g) at 140C for 4 hours. The mixture was cooled, filtered and the solids washed with dry ether. Then the solids were mixed with. 3-carhoxymethyl-2-thio-thiazolid-4-one (10 g) and pyridine (70 ml) and heated under reflux for minutes. The mixture was cooled-and poured into 90 percent aqueous ethanol (300 ml) and acidified with glacial acetic acid (65ml). After standing the crude dye was filtered off and purified by solution in 90 percent aqueous ethanol as the triethylamine salt followed by precipitation with glacial acetic acid. The product dye (13.4 g) formed dark green crystals with a melting point of 291C.

EXAMPLE 36 3-Ethyl-5 l-acetoxyethyl-S ,6-dichloro-3-ethyl-2- benzimidazolinylidene )ethylidene]-2(3-carboxymethyl-4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone 3 -Ethyl-5 l-acetoxyethyl-S ,6-dichloro-3-ethyl-2- benzimidazolinylidene)ethylidene1-2-thio-4- thiazolidone (2.0 g) was heated withdry xylene ml) and methyl toluene p-sulphonate (4.0 g) at 140C for 2 hours. The mixture was filtered and the solids washed with dry ether. The residue was mixed with 3-carboxymethyl-2-thio-4-thiazolidone (0.75 g) and dry pyridine (20 ml). After heating under reflux for 15 minutes the mixture was cooled and poured into 90 percent aqueous ethanol (200 ml). The crude dye was purified by solution in hot 90 percent aqueous ethanol (200 ml) as the triethylamine salt and precipitated by the addition of glacial acetic acid to give the product (1.0 g) with a melting point of 282C.

EXAMPLE 37 3-Ethyl-5 l,3,3-trimethyl-2-indoleninylidene)ethylidene]-2( 3-carboxy-methyl-4-oxo-2-thio-5- thiazolidinylidene )-4-thiazolidone 3-Ethyl-5[( l,3,3-trimethyl-2-idoleninylidene)ethy- 5 then I e thiazolidone (1.9g) and dry pyridine (20 ml). After lidene]-2-thio-4-thiazolidone (3.4 g) was heated with dry xylene (30 ml) and methyl toluene-p-sulphonate (6.0 g) at 140C for 2 hours. The mixture was filtered and the solids washed with dry ether. The solids were mixed with 3-carboxymethyl-2 thio-4- heating under reflux for 15 minutes the mixture was cooled and poured into percent aqueousethanol (200ml). After filtration the crude dye was purified by solution in 90 percent aqueous ethanol (200 ml) as the triethylamine salt and precipitated by the addition of glacial acetic acid to give the product dye (1.0g) with a melting point of 285C.

EXAMPLE 38 3-n-l-Iepty1-5 3-ethyl-5 -methyl-2-benzoselenazolinylidene)ethylidene]-2(3-carboxymethyl-4-oxo-2-thio-5- thiazolidinylidene-4-thiazolidone 3-n-l-lepty1-5 3-ethyl-5-methyl-benzoselenazolinylidene)ethylidene]-2-thio-4-thiazolidone (1.9g) was heated with methyl toluene p-sulphonate (4.0g) at C for 2 hours and the resulting mixture was then cooled and washed with dry ether. The residue was mixed with 3-carboxymethyl-2-thio-thiazolid-4-one (0.77g) and pyridine (20ml) and heated under reflux for 15 minutes. After this, the mixture was cooled and poured into 90 percent aqueous ethanol (200 ml). After standing, the crude dye was filtered off and purified by solution-in 90 percent aqueous ethanol as the triethylamine salt followed by precipitation with glacial acetic acid. 1

The desired product (1.4g) formed dark green crystals having a melting point of 291C.

EXAMPLE 39 A dry silver light-sensitive material was prepared by first dispersing silver behenate (67 g) in a methyl ethyl ketone-toluene mixture (1:1 by weight) so as to give a 15 percent by weight solids suspension. The dispersion was effected by ball-milling for 24 hours. Then 20 ml of a 2 percent solution of HgBr in methanol was added to form some silver bromide in the mixture. After the addition of the HgBr solution, the now light-sensitive mixture was allowed to digest for 1 hour in safe light.

- Next, a 15 percent solution (67 g) of polyvinyl butyral (Butvar 8-76) in methyl ethyl ketone and lpthalazone (0.7 g) were added and the resulting suspension ball milled for 3 hours. Thereafter, the reducing agent Nonox WSO (5.0 g) and a 0.1 percent solution (10 ml) of the Dye as prepared in Example 1 in chloroform were added and the final suspension was agitated for 102 minutes.

The suspension wasthen wet coated to 4 mil wet thickness on a polyester film base. The coating was allowed to air dry for 2 hours giving a light-sensitive material.

After exposure of the light-sensitive material to a light image, it was developed by heating for, 10 seconds at 134C to give a good negative reproduction of the light image, the developed material having a low fog and reasonable speed. The exact value for the speed was measured with respect to'the speed obtained with an excellent known green control dye of the following structure Additionally the wavelength of maximum sensitivity of the light-sensitive material was also measured. v

This procedure was then repeated using, in place of 1'0 the dye prepared in Example 1, each of the dyes as prepared in Examples 2to 29. Similar results were achieved.

For comparison, the procedure was also repeated without any dye whatsoever. 1

All of the results obtained are shown in the following Table.

Dye used Wavelength of Relative log speed (Ex. No.) maximum sensitivity to the standard measured (A max; nm/\) at the respective A max, white light exposure.

No dye 450 -1.25 Control 525 0 l 650 0.60 2 700 0.60 3 625 1.05 4 625 0.45 5 700 0.15 6 600 0.30 7 610 0.60 s 600 0.60 I 9 625 0.15 10 590 1.20 11 600 0.30 12 600 0 13 630 0.60 14 700 0.15 15 650 0.30 16 600 0.30 25 700 0.15 26 680 0.90 27 660 0.30 28 '645 0.30 29 650 0.30

As can be seen the incorporation of the known control dye in the light-sensitive compositions gives a large increase in speed, but the speed of the compositions of the invention is generally much faster and the wavelength of maximum sensitivity is at much longer wavelengths (in the region of yellow to red instead of in the green region) in comparison with the known dye.

What is claimed is: l. A light-sensitive composition comprising an intimate mixture of a substantially light-insensitive silver salt of an organic acid which upon reduction gives a visible change and sufficient of a silver halide to catalyze this reduction to give a visible change in those areas where the silver halide has been exposed to light and the mixture is heated in the presence of a reducing agent for said light-insensitive silver salt, said mixture further including a merocyanine tri-nuclear dye having the general formula: 0

(Q)kC=(CHCR )m=C c= oH-oru)..=c

in which k and l are each 0 or 1 with proviso that, when k is 0, l is 1 and when k is l, l is 0; Q represents -S, -Se, CH=Ci-l--,

where R represents a lower alkyl group or a lower alkyl group containing an ester group; m and n are each 0 or 1, R represents an alkyl, hydroxyalkyl, carboxyalkyl or sulfo-alkyl group, R represents an aryl or aralkyl group or any of the groupings represented by R; R and R each independently represents a hydrogen atom or a lower alkyl group, X and Y each independently represents a hydrogen or halogen atom or a lower alkyl, alkoxy, aryl, amino or acylamino group or together represent a divalent methylene dioxy group or the carbon atoms required to form a fused on carbon ring, and Z represents in which R and R each independently represents a.

hydrogen atom or any of the groupings represented by R including the groupings RCOOH and RSO H wherein R represents a lower alkylene group.

2. The composition of claim 1 wherein Q represents --S, -SE- or -CH=CH, Z represents -S,

and R and R each independently represents any of the groupings represented by R including the groups RCOOH and R SO H where R" represents a lower alkylene group.

3. The composition of claim 1 wherein said merocyanine dye is 3-ethyl-5[(3-ethyl-2-benzothiazolinylidene)ethylidene]-2(3-ethyl-4-oxo-2-thio-5r thiazolidinylidene)-4-thiazolidone.

4. The composition of claim 1 wherein said merocyanine dye is 3-ethyl-5[( l-ethyl-1,2-dihydroquinolinylidene-Z)ethylidene]-2(3-carboxymethyl-4-oxo-2- thio-S-thiazolidinylidene)-4-thiazolidone.

5. The composition of claim 1 wherein said merocyanine dye is 3-n-heptyl-5[(3-ethyl-2- benzothiazolinylidene)ethylidene]-2(3-carboxymethyl-4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone.

6. The composition of claim 1 wherein said merow cyanine dye is 3-ethyl-5 5-chloro-3-ethyl-2- benzothiazolinylidene )ethylidene -2( 3-carboxymethyl-4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone.

7. The composition of claim 1 containing from 0.01 to 2.0 g of said merocyanine dye per gram mole of total silver in the composition.

8. The composition of claim 7 containing from 0.4 to 1.0 g of the merocyanine dye per gram mole of total silver in the composition.

3; The composition of claim 1 wherein said silver halide is present in an amount of from 0.1 to percent by weight of the mixture of silver compounds.

10. The composition of claim 1 additionally compris- 13. A sheet-like, light-sensitive recording element comprising a support bearing at least one light-sensitive layer comprising a mixture of a substantially light-msensitive silver salt of an organic acid which upon ing a reducing agent for said light-insensitive silver 5 reduction gives a visible change and sufficient of a compound. silver halide to catalyze said reduction in those areas 11. A sheet-like, light-sensitive recording element where said silver halide has been exposed to light and comprising a support hearing at least one light-sensitive the mixture heated thepresence of a reducing agent layer comprising, in intimate mixture, for said light-insensitive silver salt, said mixture further a. a light-insensitive silver salt of an organic acid i ud g ya dy ft la:

(Q)k- =(CH0R )...=c o= cH-,om ..=o /c=s l C CH w E H: I? )1 0 R 6 RI Y R which upon reduction undergoes visible change,

b. silver halide in an amount sufficient to catalyze the reduction of said light-insensitive silver compound after exposure of said element to a light image and upon heating of the element in the presence of a reducing agent for said light-insensitive silver compound, and.

c. a tri-nuclear merocyanine dye of the formula in which and l are each 0 or 1 with the proviso that, when k is 0, l is l and when k is 1, I is 0; Q represents S, Se, CH=CH, O-,

in which k and l are each 0 or 1 with the proviso that, when k is 0, l is l and when k is 1, l is 0; Q represents S, Se, CH=CH-, O--,

where R represents a lower alkyl group or a lower alkyl group containing an ester group; m and n are each bon atoms required to form a fused on carbon ring, and

Z represents R O R in which R and R each independently represents a hydrogen atom or any of the groupings represented by R including the groupings RCOOH and R'SO l-l where'R represents a lower alkylene group.

12. The recording element of claim 11 additionally including a layer containing a reducing agent for said light-insensitive silver salt in contact with said light-sensitive layer.

alkyl group containing an ester group; m and n are each 0 or 1, R represents an alkyl, hydroxyalkyl, carboxyalkyl or sulfo-alkyl group, R represents an aryl or aralkyl group or any of the groupings represented by R; R and R each independently represents a hydrogen atom or a lower alkyl group, X and Y each independently represents a hydrogen or halogen atom or a lower alkyl, alkoxy, aryl, amino or acylamino group or together represent a divalent methylene dioxy group or the carbon atoms required to form a fused on carbon ring, and Z represents R 0 R s-, -0-, 411- ii-fvin which R and R each independently represents a hydrogen atom or any of the groupings represented by R including the groupings RCOOH and RSOJ-l wherein R represents a lower alkylene group.

14. A sheet-like, light-sensitive recording element comprising a support bearing at least one light-sensitive layer comprising, in intimate mixture,

a. a' substantially light-insensitive silver salt of an organic acid which upon reduction gives a visible change,

b. silver halide in an amount sufficient to catalyze the reduction of said light-insensitive silver salt after exposure of said element to a light image and upon heating of the element in the presence of a reducing agent for said light-insensitive silver salt, and

c. a tri-nuclear merocyanine dye of the formula where R represents a lower alkyl group or a lower alkyl group containing an ester group; m and n are each or 1, R represents an alkyl, hydroxyalkyl, carboxyalkyl or sulfo-alkyl group, R represents an aryl or aralkyl group or any of the groupings represented by R; R and R each independently represents a hydrogen atom or a lower alkyl group, X and Y each independently represents a hydrogen or halogen atom or a lower alkyl, alkoxy, aryl, amino or acylamino group or together represent a divalent methylene dioxy group or the carbon atoms required to form a fused on carbon ring, and Z represents in which R and R eachindependently represents a hydrogen atom or any of the groupings represented by R including the groupings R COOl-l and RSO l-l wherein R represents a lower alkylene group, with the proviso that R and R or both R and R represent the v grouping RCOOl-l or R SO l-l. 4

15. The recording element according to claim 14 wherein, in said merocyanine dye, Q represents S, Se-, or CH=CH, and Z represents S,

W 'R 5 o R5 'I1I OX 16. The recording element according to claim l4 wherein said merocyanine dye is 3-Ethyl-5[(l-ethyll ,2-dihydroquinolinylidene-2)ethylidenel-l (3-carboxymethyl-4-oxo-2-thio-5-thiazolidinylidene)-4- thiazolidone.

17. The recording element according to claim 14 wherein said merocyanine dye is 3-n-Heptyl-5[(3- ethyl-Z-benzothiazolinylidene)ethylidenel-Z(3-carboxymethyl-4-oxo-2-thio-5thiazolidinylidene)-4- UNITED STATES PATENT OFFICE QERTEFICATE OF CORRECTION Patent No. 3,719 495 Dated March 6 1973 Invent Bernard A. Lea.

r appears in the above-identified patent It is certified that erro re hereby corrected as shown below:

and that said Letters Patent a C01. 3, line 21, "recoding" should be --recording--.

Col. 6, Example 3, line 56, "3-carboxymethy1-2 4- thlazolidone" should be --3-carboxymechyl-2-thio-M-thiazolidone- Col. 7, Example 2 3, line 66, after "-2-thio-5" and before "[(3", add -#chiazolidinylidene)- b-chiazolidone.

3-Carboxymethyl-5 Col. 8, Example 10, line 37, "IS-carboxymethyl- ZM-one" should be -3-carboxymethyl-2-thio-thiazolid- 4-one-.

Col. 11, Examplei2l, line 31, after "(20" add Attesting Officer Acting; Commissioner of Patents Col. ll, Examplel 22, line 58, "wit" should be --with-. l

, I Col. 12, Example 25, line 16, "wit" should be --with-. i

1 Col. 12, Example! 25, line 53, "cooking" should be -cooling--. i 1 Signed and sealed this 18th day of December 1973.

l (SEAL) Attest:

EDWARD M. FLETCHER, JR. RENE D. TEGTMYER USCOMM-DC 60376-P69 d u 5 GOVERNMENT Pmm'mo OFFICE I969 0-366-334 F ORM PO-105O (10-69) 

1. A light-sensitive composition comprising an intimate mixture of a substantially light-insensitive silver salt of an organic acid which upon reduction gives a visible change and sufficient of a silver halide to catalyze this reduction to give a visible change in those areas where the silver halide has been exposed to light and the mixture is heated in the presence of a reducing agent for said light-insensitive silver salt, said mixture further including a merocyanine tri-nuclear dye having the general formula:
 2. The composition of claim 1 wherein Q represents -S-, -SE- or -CH CH-, Z represents -S-, and R4 and R5 each independently represents any of the groupings represented by R1 including the groups R7COOH and R7SO3H where R7 represents a lower alkylene group.
 3. The composition of claim 1 wherein said merocyanine dye is 3-ethyl-5((3-ethyl-2-benzothiazolinylidene)ethylidene)-2(3-ethyl-4-oxo-2 -thio-5-thiazolidinylidene)-4-thiazolidone.
 4. The composition of claim 1 wherein said merocyanine dye is 3-ethyl-5((1-ethyl-1,2-dihydroquinolinylidene-2)ethylidene)-2(3 -carboxymethyl-4-oxo-2-thio-5-thiazolidinylidene)-4-thiazolidone.
 5. The composition of claim 1 wherein said merocyanine dye is 3-n-heptyl-5((3-ethyl-2-benzothiazolinylidene)ethylidene)-2(3-carboxymethyl -4-oxo-2-thio-5-thiazolidinylidene)-4-thiazolidone.
 6. The composition of claim 1 wherein said merocyanine dye is 3-ethyl-5((5-chloro-3-ethyl-2-benzothiazolinylidene)ethylidene)-2(3 -carboxymethyl-4-oxo-2-thio-5-thiazolidinylidene)-4-thiazolidone.
 7. The composition of claim 1 containing from 0.01 to 2.0 g of said merocyanine dye per gram mole of total silver in the composition.
 8. The composition of claim 7 containing from 0.4 to 1.0 g of the merocyanine dye per gram mole of total silver in the composition.
 9. The composition of claim 1 wherein said silver halide is present in an amount of from 0.1 to 10 percent by weight of the mixture of silver compounds.
 10. The composition of claim 1 additionally comprising a reducing agent for said light-insensitive silver compound.
 11. A sheet-like, light-sensitive recording element comprising a support bearing at least one light-sensitive layer comprising, in intimate mixture, a. a light-insensitive silver salt of an organic acid which upon reduction undergoes visible change, b. silver halide in an amount sufficient to catalyze the reduction of said light-insensitive silver compound after exposure of said element to a light image and upon heating of the element in the presence of a reducing agent for said light-insensitive silver compound, and c. a tri-nuclear merocyanine dye of the formula
 12. The recording element of claim 11 additionally including a layer containing a reducing agent for said light-insensitive silver salt in contact with said light-sensitive layer.
 13. A sheet-like, light-sensitive recording element comprising a support bearing at least one light-sensitive layer comprising a mixture of a substantially light-insensitive silver salt of an organic acid which upon reduction gives a visible change and sufficient of a silver halide to catalyze said reduction in those areas where said silver halide has been exposed to light and the mixture heated in the presence of a reducing agent for said light-insensitive silver salt, said mixture further including a merocyanine dye of the formula:
 14. A sheet-like, light-sensitive recording element comprising a support bearing at least one light-sensitive layer comprising, in intimate mixture, a. a substantially light-insensitive silver salt of an organic acid which upon reduction gives a visible change, b. silver halide in an amount sufficient to catalyze the reduction of said light-insensitive silver salt after exposure of said element to a light image and upon heating of the element in the presence of a reducing agent for said light-insensitive silver salt, and c. a tri-nuclear merocyanine dye of the formula
 15. The recording element according to claim 14 wherein, in said merocyanine dye, Q represents -S-, -Se-, or -CH CH-, and Z represents -S-,
 16. The recording element according to claim 14 wherein said merocyanine dye is 3-Ethyl-5((1-ethyl-1,2-dihydroquinolinylidene-2)ethylidene)-1(3 -carboxymethyl-4-oxo-2-thio-5-thiazolidinylidene)-4-thiazolidone.
 17. The recording element according to claim 14 wherein said merocyanine dye is 3-n-Heptyl-5((3-ethyl-2-benzothiazolinylidene)ethylidene)-2(3-carboxymethyl -4-oxo-2-thio-5-thiazolidinylidene)-4-thiazolidone. 